1. Field of the Invention
The present invention relates to the field of back supports. More particularly, the present invention relates to back supports that support a person""s lumbar spine and associated muscle groups. More particularly still, the present invention relates to such back supports that are pneumatic and embedded in upholstered seat backs.
2. Description of Related Art
Many previous inventions have been directed to the support of the lumbar spine. One class of these involves the use of one or more fluid-filled bladders (i.e., fluid cells) that are placed beneath the fabric of a backrest. Examples of this class are disclosed in Schmidt (U.S. Pat. No. 5,893,609; 1999), which discloses an inflatable lumbar support system that includes an inflatable air cell coupled to a motorized pump, and Ishida et al. (U.S. Pat. No. 4,807,931; 1989), which discloses a lumbar support system very similar to that of Schmidt except for the substitution of a hand-operated pump for the motorized pump. The inflatable cell that supports the lumbar region in the systems according to Schmidt and Ishida et al., and virtually all other known inflatable-cell lumbar support systems, is typically constructed as a simple pillow-like device that, when inflated, has a maximum thickness dimension in the center of the device that gradually and evenly slopes to a minimum thickness at the edges of the device. As a result, the conventional lumbar-support systems of the types disclosed by Schmidt and Ishida et al. fail to constrain the expansion or inflation of the inflatable device to only the lumbar-supporting surface contour of the backrest, and/or fail to provide sufficiently pronounced change in contour to provide adequate and comfortable differential pressure needed in the lumbar region.
Certain inventions within the expandable-fluid-cell class directed to overcoming the above-noted limitation have attempted to provide systems that produce the desired degree of change in the back-support topology that is needed for effective lumbar relief. Among these are Noble (U.S. Pat. No. 4,840,425; 1989) and Lorbiecki (U.S. Pat. No. 5,975,629; 1999). The support systems disclosed therein provide multiple inflatable cells that are small relative to the area of the seat and of the lumbar region of a seat occupant. Consequently, the ability of the inflatable cells to extend outward into the lumbar region of the the seat occupant""s back is accordingly small and fails to adequately focus the expansion of the seat backrest on the lumbar region to provide the needed relief and comfort. By xe2x80x9cfocusxe2x80x9d is meant providing for a pronounced or abrupt change in the surface contour of the backrest and restricting this change to a pre-defined particular area.
Another class of existing lumbar-support systems uses rotatable cams or rods to displace a portion of a seat back. One such system is that of Beaulieu (U.S. Pat. No. 6,092,871; 2000), which teaches a lumbar support system embedded in the upright portion of an office chair. The Beaulieu support includes an arcuate lumbar plate, the degree of convexity of which is varied by operating an underlying swing-arm and spring assembly. Just as with the fluid-cell class of supports, the mechanically extendable system of Beaulieu produces a smooth, relatively gradual and continuous change in the surface contour of the backrest. A more pronounced transition (i.e. discrete jump) from one area to an adjacent area is not possible. This class of lumbar support systems, while using alternative expansion means to those of the fluid-cell class of support systems, likewise does not adequately focus the expansion of the seat backrest in the lumbar region.
What is needed therefore is device that provides pronounced expansion of the backrest in the region corresponding to the lumbar region of the person using the backrest. What is further needed is such an device that allows for relatively abrupt changes in the surface contour of a lumbar support area of a backrest. Finally, what is needed is such device that can be built into the backrest of a traditional seat.
It is an object of the present invention to provide a device in a backrest for the expansion of a back-support that provides an improved adaptability of a back-support to the body contour of an occupant. It is a further object of the present invention to provide such a device that will provide an abrupt change in surface contour of the backrest in a particularly defined area of the backrest. It is a further object to provide such a device for the expansion of a back-support surface in the lumbar region.
The objects are achieved by providing a back-support device according to the present invention that comprises an accordion-pleated section of material that is positioned on the backrest between a conventional expansion or inflation means that is embedded in the backrest and the back of an occupant of the backrest. The backrest may be the backrest, for example, of an upholstered chair or automobile seat, a lounge, or a bed or other type of support devices for a body and any subsequent references herein to a xe2x80x9cseatxe2x80x9d also include these support devices. The back-support device is constructed as an accordion section comprising multiple pleats that are formed by offset or overlapping folds of a fabric. In one embodiment, the folds extend in a direction transverse to the vertical axis of the backrest, so as to form a cascade of pleats that extends from a top edge of the back-support device to a bottom edge. In an alternative embodiment, the folds extend in a direction parallel to the vertical axis of the backrest. Depending on the particular application of the device according to the present invention, it is possible to form an accordion-pleated backrest support wherein the folds extend in a direction that is diagonal or at some other angle relative to the vertical axis of the backrest. The direction of the folds is not critical to the present invention. Rather, it is the plurality of pleats in the fabric of the back-support device according to the present invention that provides a back-support that is highly variable and, thus, adaptable to the body contour of the occupant and consequently provides a greater particularly localized distention of the back-support device than does the prior art.
The fabric may be from any of a range of materials, including but not limited to leather, natural fibers, synthetic material, woven or non-woven material, and the like. The back-support device is attached along its sides to the backrest, and the sides, the top edge and the bottom edge together define the limits of the expandable (distendable) area. The xe2x80x9couter facexe2x80x9d of the back-support device faces outward toward the occupant, and the xe2x80x9cinner facexe2x80x9d of the section faces inward toward the expansion means. In one embodiment, particularly if the fabric used is leather, each pleat is stitched with a top-stitch that runs along the pleat near the edge of the fold. In this manner, top-stitching placed near a first fold, for example, is visible on the face of the back-support device, whereas the top-stitching near one or two folds respectively adjacent to the first fold is visible on the back of the back-support device, i.e., the side facing the expansion means of the fabric. The pleats of the back-support device are expandable from a non-expanded, relatively flat condition outward away from the backrest and toward an occupant""s back, in response to pressure applied by the expansion means, and then fold back again to the non-expanded condition when the expansion means retracts. The expansion of the backrest is thereby confined to only the area defined by the back-support device and, because of the configuration of the pleats, the change in surface contour of the backrest is very pronounced or abrupt in the inflated or expanded area, rather than even and gradual, as is the case with conventional lumbar-support devices.
As stated above, the back-support device is used in conjunction with an expansion means. The expansion means is not limited to any particular type; the necessary quality of it merely being that it move the back-support device towards a person""s back. The present invention will have increased utility as new expansion means are devised.